1. Field of the Invention
This invention relates to a communication terminal apparatus connected to an ISDN, i.e. an Integrated Services Digital Network, confidentiality processing as well as the recording of information relating to the destination of a received document. The invention relates also to a communication method using such a communication terminal apparatus.
2. Description of the Prior Art
A confidential service using a communication terminal apparatus is utilized in the transmission of document information requiring the maintenance of secrecy.
A typical example of a communication terminal apparatus for sending and receiving confidential messages is a facsimile apparatus. When a confidential document is received, a communication terminal apparatus such as a facsimile apparatus used in confidential communication operates to store the received document as a confidential document in response to an instruction from a sending terminal possessing a confidential document transmission function. The document stored as the result of confidentiality processing can be extracted after processing from a so-called memory box (storage device), with which the terminal on the receiving side is equipped, by a specific person using a specific number.
In a conventional facsimile apparatus, only an indication of the sender's number, namely the number of the party sending the document, is provided as additional information recorded along with the received document.
Thus, the conventional communication terminal apparatus is such that unless the sending side possesses a confidential document transmission function, the sending and receiving of confidential documents, namely confidential communication, cannot be carried out even if the receiving side has memory means such as a memory box and a confidential document receiving function. As a result, a limitation is imposed upon the number of users capable of utilizing a confidential service.
If an attempt is made to perform a confidential transmission between two parties, the sending side must specially install an apparatus having the confidential document transmission function, and the receiving side must specially install an apparatus having the confidential document receiving function. Further, though the identity of the sending party is known with the above-mentioned conventional facsimile apparatus, there are cases in which one facsimile apparatus is used jointly by a plurality of persons and the name of the party to receive the document is not written on the received document as its destination. In such cases, whom the document is intended for is unclear unless the contents of the received document are read.